Infection with human immunodeficiency retrovirus (also known as HTLV III, LAV,. and ARV) can produce a spectrum of immunologic perturbations ranging from no obvious deficit to severe combined acquired immune deficiency. Adults with acquired immune deficiency syndrome are likely to have lymphopenia and severe cell-mediated immunodeficiency, with a dramatic deficiency of helper T cells. Adults also have hypergammaglobulinemia and diminished capacity to produce antibody after primary or booster immunizations? Even asymptomatic HIV-infected adults have defective B-lymphocyte function as measured by a variety of in vitro assays. 2 In chiidren, HIV infection produces a similar spectrum of immunologic perturbations. A recent study of sick children with AIDS has demonstrated blunted antibody responses to bacteriophage phi X174 after prinmry and secondary immunizations. In addition, class switching (IgM to IgG) was generally absent and antibody responses to pneumococcal vaccine and tetanus toxoid were also diminished? We examined 17 children with HIV infection, who had received at least three immunizations with diphtheriatetanus-pertussis vaccine, for the presence of humoral and ceil-mediated immune responses to diphtheria and tetanus toxoids. These children had neither, a history of opportunistic infection nor biopsy-proved lymphocytic interstitial proliferation at the time of study. METHODS